Caterpillar 797
The Caterpillar 797 is a series of off-highway, ultra class, two-axle, mechanical powertrain haul trucks developed and manufactured in the United States by Caterpillar Inc. specifically for high production mining and heavy-duty construction applications world-wide. In production since 1998, the 797 series represents Caterpillar’s largest, highest capacity haul trucks. The current, third-generation model, the 797F, offers one of the largest haul truck payload capacities in the world, up to and is the world's largest, highest payload capacity, mechanical drive haul truck. Initial development In 1997, Caterpillar tera decided to begin development of a payload capacity haul truck to meet the demand from large-scale mine operators wanting to reduce operating costs at mines using 80 to 90 short tons (73 to 82 t) per pass shovels. Engineers at Caterpillar's Mining & Construction Equipment Division in Decatur, Illinois created a new design for the 797 using computer-aided design technology. This was the first time CAD tools had been used extensively to design a Caterpillar truck. 797 (1998 - 2002) Caterpillar first unveiled a completed 797 on September 29, 1998 at the Decatur, Illinois assembly plant. Testing The first two 797's produced were transported to Caterpillar's Arizona proving grounds for testing. In the second quarter of 1999, the third and fourth 797's produced were the first to be placed in service with a customer at the Bingham Canyon Mine in Utah. Caterpillar put 18 additional 797's into service with mine operators world-wide as production development units. Full worldwide marketing Caterpillar began marketing the 797 in North America in 2000, with full world-wide marketing following in 2001. 797B (2002 - 2009) Caterpillar introduced the 797B in spring of 2002, replacing the first-generation 797. Caterpillar increased the power output of the Cat 3524B engine to cope with the 797B's higher payload capacity of up to , a improvement over the 797. The first 797B units entered service with customers in October, 2002. 797F (2009 - Present) Caterpillar introduced the latest 797 in the series, the 797F, at MINExpo International in September, 2008. When Caterpillar began full production of the 797F in late 2009, the 797F replaced the 797B. The 797F comes equipped with a new, more powerful and more efficient Cat C175-20 engine and an increased payload capacity of up to . Powertrain The Caterpillar 797 series trucks employ mechanical drive powertrains in contrast to the diesel-electric powertrains of similar haul trucks offered by competitors. During initial development in 1997, a diesel-electric powertrain was considered for the 797, but this powertrain configuration was not developed because Caterpillar considered a mechanical drive powertrain more appropriate for market conditions at that time. 797 engine A gross Cat 3524B HD EUI 24-cylinder, high displacement, electronic unit injection, quad single-stage turbocharged, aftercooled, four-stroke diesel engine powers the 797. The Cat 3524B HD engine is a tandem unit consisting of two 12-cylinder Cat 3512B HD engine blocks coupled to operate as a single engine. 797B engine A gross , twin turbocharged version of the Cat 3524B engine powers the 797B. The power rating of the 3524B is valid up to an elevation of or with a high altitude arrangement. 797F engine A gross Cat C175-20 ACERT single block, 20-cylinder, electronic common rail injection, quad turbocharged, air-to-air aftercooled, four-stroke diesel engine powers the 797F. The power rating of the C175-20 is valid up to an elevation of or up to with a high altitude arrangement. Transmission The 797 series haul trucks are equipped with a rear axle mounted, computer controlled, seven speed planetary transmission with an integral lock-up torque converter. Wheels and tires Each 797 wheel is attached to the axle using 47 nuts that are torqued to . A size 55/80R63 radial tire was developed by Michelin in conjunction with Caterpillar specifically for the first generation 797. The Caterpillar 797B and 797F run on the largest tire in the world, the tall, Michelin 59/80R63 XDR. Six tires are required per truck at a cost in 2009 of approximately USD $42,500 per tire. Manufacturing and assembly Major components of the 797 are manufactured and assembled at six Caterpillar or supplier facilities located throughout North America, then shipped to the customer site for final assembly by Caterpillar technicians. The engine is manufactured by Caterpillar in Lafayette, Indiana and is then shipped to Caterpillar's Decatur, Illinois assembly plant. The tires are manufactured by Michelin North America at the US7 Earthmover Manufacturing plant in Lexington, South Carolina and are shipped to the customer site. The driver's cab is manufactured by Bergstrom Climate Control Systems' Contract Assembly division in Joliet, Illinois. Each cab is assembled by one person and requires forty hours to complete. The cab is shipped to the customer site. The dump body is composed of five components: the floor, the two sides, the front wall and the canopy. The dump body is shipped in component form to the customer site where it is assembled and welded into a monolithic structure before being joined to the frame during final assembly. The frame is created from nine individual metal castings manufactured by Amite Foundry and Machine Inc. in Amite City, Louisiana. The smallest casting weighs and the largest casting weighs . The rough castings are shipped to the Caterpillar Decatur, Illinois assembly plant. At Caterpillar's Decatur, Illinois assembly plant, the frame is assembled and the powertrain is installed and tested. The nine castings that compose the frame are machined to provide clean welding surfaces. The castings are placed in a jig and are initially joined by human welders. The frame is moved to a second welding station for further welding by robots. The third and final welding stage is completed by human welders. To ensure quality, welds are tested using an ultrasonic flaw detector. In total, of welding wire is used to join the individual castings into a monolithic frame. After the frame assembly is completed, production workers attach hydraulic lines and electrical wiring to the frame before installing the engine and rear axle . The frame/powertrain assembly is tested and then partially disassembled to facilitate shipping from Caterpillar's Decatur, Illinois assembly plant to the customer site. Transportation The engine, frame, axles and differential requires six to seven semi-trailer truck loads, the cab requires one semi-trailer load, the six tires require two semi-trailer loads and the dump body requires four semi-trailer loads. In total, one 797 requires 12 to 13 semi-trailer truck loads that originate at various manufacturing facilities and deliver to the customer site. If a 797 must be moved from one job site to another for any reason, it can not be driven on public roads due to its exceptional size and weight. Moving a 797 requires dis-assembly, loading on to semi-trailer trucks, transport and re-assembly at the new location. Final assembly Final assembly of the 797 is completed by Caterpillar field mechanics at or near the customer site. Before the dump body can be joined to the frame, the dump body components must be assembled and welded together by a dedicated team, requiring seven to ten days per dump body. Final assembly of one 797 requires a team of seven mechanics working in three shifts around the clock, seven days per week for 20 days in addition to the time required to assemble and weld the dump body. Cost Although the price varies based on individual customer specifications, each 797 costs approximately USD $5,000,000. Service life All major components of the 797 can be serviced or replaced during the useful life of the truck, except for the frame. The overall service life of the truck is therefore dependent upon the durability of the frame which Caterpillar estimates to have a twenty year service life. Competition The Liebherr T 282 B and Bucyrus MT6300AC both match the Caterpillar 797F's payload capacity, but employ diesel/electric powertrains in contrast to the 797F's diesel-powered, mechanical powertrain. Depending on customer requirements, lower payload capacity products such as the Komatsu 960E-1 may also place competitive pressure on sales of the 797F. Comparison chart See also * Bucyrus MT6300AC * Komatsu 960E-1 * Liebherr T 282B * Belaz 75600 * Terex 33-19 "Titan" * Haul truck References External links * Caterpillar 797B Mining Truck - Caterpillar Inc. * Caterpillar 797F Mining Truck - Caterpillar Inc. * 2009 F-Series Mining Trucks Press Kit - Caterpillar Inc. * Product Safety > Off-Highway Tractors and Trucks - Caterpillar Inc. * Viewpoint - Perspectives on Modern Mining - Caterpillar Inc. * XDR Radial Tires - Earthmover Tires by Michelin - Michelin North America, Inc. * Bergstrom Climate Systems Contract Assembly Division - Bergstrom Inc. Category:Off-road vehicles Category:Mining equipment Category:Caterpillar dump trucks Category:Caterpillar 797 mining truck Category:Ultra class haul trucks Category:797 (model number) Category:Trucks built in the United States